Fabrication of tapered pipe



LMay 30, 1967 F. E. GRATE 3,321,945

FABRICATION OF TAPERED PIPE May 30, 1967 F. E. GRATE 3,321,945

FABRICATION OF TAPERED PIPE Filed May 5, 1964 2 Sheets-Sheet .2

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United States Patent 3,321,945 FABRICATEON OF TAFERED PIPE Franlr E. Grate, Cincinnati, Ohio, assigner' to The Wilahmson Company, Cincinnati, Ohio, .a corporation of Filed May 5, 1964, Ser. No. 365,033 3 Ciaims. (Ci. 72u51) This invention relates to a method of fabricating tapered round pipe from sheet metal. Such pipe is provided in various lengths and diameters for use as air conduits in heating and cooling systems. The taper is slight, being approximately one-eighth of an inch over an average length. Even so, tapered pipe has a distinct advantage over non-tapered pipe, because less crimping, done at the smaller end in tapered pipe, is required in order to make joints. As a consequence, less turbulence is created at the joints when tapered pipe is used in an air conduit system, with a substantial reduction in resistance to air tiow.

Both straight pipe and tapered pipe are formed from flat sheets of metal. As a iirst step in the fabrication, the two long edges are configurated to form interconnectable parts of a seam. The flat sheets are then rounded into a cylinder and then, in ea-ch instance, one end is crimped. It is conventional to ship pipe with the seams unjoined. In this way, a number of lengths of pipe may be nested, thereby reducing shipping costs. The interconnectable edgewise configurations that form the seams are such` that they may be snapped together by the installer on the job.

In the formation of straight lengths of pipe, it has been conventional to fabricate the interconnectable edges by the use of a roll forming machine, `a plurality of rolling mills being arranged to progressively fold and crimp both edges simultaneously as the sheet passes through the machine. This is an inexpensive method, being fast and requiring a minimum of labor.

However, to my knowledge, there has been no way of using a roll forming machine to simultaneously fabricate the interlockable edges of a sheet of the type used for tapered pipe, because of the simple fact that the side edges of the blank sheets used heretofore have not been parallel to one another. Conventionally, the side edges of a sheet to be made into tapered pipe have been fabricated on press-brakes in an operation in which the sheets are handled by hand. This is a comparatively slow method -and expensive, due to labor costs.

The primary objective ofthis invention has been to Y provide a method and means whereby tapered pipe can be fabricated as economically as straight pipe using roll forming machines.

This objective has been fuliilled by making a modification in a conventional roll forming machine. A machine of this type has two lines of driven rolling mills rotatably mounted in heads that parallel one another at the sides of the path of movement of the sheet metal through the machine. In forming straight pipe, the heads are held rigidly stationary. l have discovered that these heads, while remaining parallel to one another, can be shifted slightly away from one another progressively during the passage of a sheet of metal between them and that a taper results in the iinis-hed pipe. Further, the movement need only be relative. That is, either one of the heads may be moved while the other is held stationary, or both heads may be moved. The movement is only oneeighth of an inch and it can be controlled automatically through the use of limit switches with the drive means for effecting such movement being triggered by the sheet of metal as it is passing through the machine.

Other objectives and advantages will be readily apparent to those skilled in the art from the following detailed description of the drawings in which:

3,3%,945 Patented. May 30, i967 FIGURE 1 is a diagrammatic view of a conventional roller die machine as modified to practice the method of this invention.

FIGURE 2 is a side elevational View thereof.

FIGURE 3 is a plan view of a sheet of metal from which tapered pipe is formed using the conventional press-brake method.

FIGURE 4 is a fragmentary cross sectional View taken on the line 4-4 of FIGURE 3.

FIGURE 5 is a fragmentary cross sectional view taken through the seam used in both tapered and straight pipe, this same type of seam resulting from fabrication using the method of this invention.

FIGURE 6 is a perspective View showing a length of tapered pipe.

FIGURE 7 is a plan view showing a `sheet of metal with the side edges fabricated by the method of this invention.

Reference is first made to FIGURE 3 of the patent drawings which is representative of a lflat sheet of metal having the opposite side edges configurated to provide the interconnectable parts I() and 1l of a seam of the type illustrated at l2 in FIGURE 5. This sheet starts out initially as `a tapered sheet, the dimension lA at the left end being approximately one-eighth of an inch smaller than the dimension B at the right end. This same relationship holds true in the sheet after the edge configurations 1t) and 1.1 have been fabricated. Because of this taper, it has been impossible heretofore simultaneously to form the edge congurations 10 and .l1 through the use of conventional roll forming machines. This -igure is representative of the prior art wherein a pressbrake machine is used to fabricate the interconnectable parts of the seam.

The conguration 10 -comprises a groove into which the bead configuration at 11 snaps when the seam is formed. Other configurations are possible and it is well within the skill of the art to provide them utilizing known roll forming machines. A roll forming machine is shown diagrammatically at 13. This machine, except for the modifications to be described below, is one that may be purchased on the open market. It includes a base 14- upon which is mounted a pair of heads shown generally at ILS-16 The head l5 that is in the upper part of FIGURE 1 is stationary in the instance shown. It includes two vertical journals 17-l7 that are disposed in spaced parallel relation. The rolling mills are indicated at 18 and following conventional practices they are congurated to progressively form one of the interconnectable: parts of the seam such as the one designated lil in FIGURE 3. All of the rolling mills are mounted on shafts 19 `and these shafts are rotated by means of an interconnected drive not shown. Since the configuration of the rolls themselves may vary depending upon the type of seam to be used, and since this matter is one within the skill of the art, the rolling mills are shown diagrammatically only and without any specific contguration. This same construction is repeated in the head 16. A sheet of metal to be fabricated is fed through a machine from right to left as shown in FIGURE 1. The sheet passes over a bed 20 made up of a series of slats, there being five of these slats shown with the edgewise slats 21-21 having ribs 22--22 thereon to serve as guides for the opposite side edges of a sheet passing through the machine. The other three slats shown at 23 function only as supports for the center section of the sheet. A sheet is driven through the machine by the rolling mills. However, after it leaves the pair of rolling mills at the left, it is then picked up and driven by two spaced sets of paired rollers. One of these sets, being shown in FIGURE 2, consists of a driven roller 24 and a holddown roller 2S. The driven roller 24 has a groove in it to receive a belt 26. This belt passes around a pulley 27 that 3 is keyed to one end of an elongated shaft 28 of a doubled ended electric motor 29. The hold-down roller 25 is rotatably mounted by a bracket 30 that is at the underside of a strap 31 hinged as at 32 to the adjacent head 15 or 16. The driven roller 24 is mounted by means of an arm 33 which is secured in turn to a bracket 34 mounted to the underside of the bed 20.

As above described, the machine is adapted to form the interconnectable edgewise configurations of a nontapered pipe. The rectangular sheet is simply fed in at the right end of the machine and it emerges at the left, passing in a straight line between the heads 15 and 16 while both of these heads are held stationary. That is, they neither move toward or away from one another as the sheet passes between the rolling mills.

By contrast, in practicing the method of this invention, the head 16 is moved outwardly away from head 15 by approximately one-eighth of an inch as the sheet is passing through the machine. The sheet is initially rectangular. This results in some savings, because it is not necessary to cut the sheet with a taper before fabrication.

The head 16 is driven by means of two screws, 35 at the discharge end of the machine, and 36 at the opposite end of the machine. These two screws thread through appropriate threaded parts of the head 16 so that as the two screws rotate simultaneously and at the same speed, the head 16 remains parallel to head 15 while moving away from it. The two screws 35 and 36 have bevel gears 37-37 at their outer ends meshing with mating bevel gears 38-38 that are keyed to a common drive shaft '39. This drive shaft is driven from a speed reduction transmission 40 at the right end of the machine, the transmission is powered by an electric motor 41 through pulleys 42 and 43 that are interconnected by means such as a belt 44. The electric motor 41 is of the reversing type so that during the pass of a sheet of metal through the machine, it rotates in a direction to shift head 16 away from head 15. In between passes7 it reverses and drives head 16 back toward head 15 to an initial starting posi tion. The limits of travel of head 16 are determined by a limit switch 45 adapted to be engaged by head 16 at its innermost position and a limit switch i6 adapted to be engaged by the head at its outermost position. These two switches are wired into the motor circuitry to stop the motor. Limit switch 45 may also be wired to energize an indicator light 47 or other indicator means to alert the operator of the machine that the machine is ready for the next sheet.

There is another important switch that is shown at 48. This switch is adapted to be activated by the passage of a sheet of metal through the machine. When the leading edge of the sheet reaches the switch 48, the motor is started to progressively move head 16 away from head 15. This switch 48 is located approximately three-fourths of the way through the machine. As may be seen in FIG- URE 2, switch 48 has a plunger i9 that projects up into the path of a sheet passing through the machine. This plunger is held `depressed during the passage of the sheet over it. When the trailing edge of the sheet passes the plunger 49, it returns to the elevated position. In doing so, it conditions the motor to run in the opposite direction after the next stop. The stop occurs when limit switch 46 is engaged by head 16 and the motor then runs in the opposite direction to return head 16 to its inner position where it is stopped by the limit switch 45.

Reference is now made to FIGURE 7 wherein a sheet of metal, having the side edges fabricated by the method of this invention, is shown. In this instance, the fabricated edge 50, shown in the upper part of the figure, is identical in cross section to the edgewise coniiguration 1t? shown in the upper part of the FIGURE 3. The configuration at the opposite side, shown at 51, is identical in cross section to the fabricated edge 11. It will be noted that the fabricated edge t) slants from one end to the other, the slant being exaggerated for illustration purposes, and although the dimensions A and B shown at the left and right ends of this figure are identical, the dimension C is smaller than either A or B by the amount that head 16 moves away from head 15, this being one-eighth of an inch in the instance shown. Thus, when the edgewise configuration 51 is snapped into the edgewise configuration 5t?, the taper of the type shown in FIGURE 6 results.

After leaving the machine, the sheet may be formed into a tubular shape and the smaller end crimped as shown at 52. At the same time, a shoulder 53 may be formed adjacent the crimped end, this shoulder providing a stop for the larger circular end of a similar length of pipe to which it is joined.

Of course, the machine should be timed such that the head 16 completed its cycle of movement away from head 15 from the time that the plunger 49 is rst depressed until the trailing edge of the sheet being fabricated leaves the rolling mills at the left of the machine as it appears in FIGURE 1. Thus, if a change in the lengths of sheets being run is required, it is necessary that the speed of the motor be changed relative to the speed of the sheet as it passes through the machine under the influence of the rolling mills. For this purpose and in order to initially time the machine, it is preferred that some means be provided to vary the speed of the motor 41. In the instance shown, the bracket 54 is mounted under the motor with a speed control device 55 thereon having a dial 56 which may be wired into the motor circuitry following known techniques.

Having described my invention, I claim:

1. The method of fabricating a tapered pipe from a rectangular sheet of metal using a roll forming machine having two lines of driven rolling mills disposed in spaced parallel relation with respect to one another extending longitudinally of said machine, and with said lines adapted to progressively and simultaneously fold and crimp opposite side edges of said sheet as said sheet passes longitudinally of said machine between said lines to form interconnectable parts of a seam comprising the steps of:

providing a rectagular sheet of metal of a size to have its opposite side edges engaged by said lines, passing said sheet between said lines longitudinally of said machine,

moving one of said lines away from the opposite line approximately one-eighth of an inch during the passage of said sheet between said lines such that the seam part formed by the moving line is displaced at an angle with respect to the axis of said rectangular sheet,

forming said sheet into a tapered cylinder,

interconnecting said interconnectable parts to form a seam, and

crimping the smaller end of the tapered pipe thus formed.

2. The method of fabricating a blank adapted to be formed into a tapered pipe from a rectangular sheet of metal using a roll rforming machine having two lines of driven rolling mills disposed in spaced parallel relation with respect to one another and extending longitudinally of said machine, and with said lines adapted to progressively and simultaneously fold and crimp opposite `Side edges of said sheet as said sheet passes longitudinally of said machine between said lines to form interconnectable parts of a seam comprising the steps of:

providing a rectangular flat sheet of metal of a size to have its opposite side edges engaged by said lines, passing said sheet between said lines longitudinally of said machine, and

moving one of said lines away from the opposite line during the passage of said sheet between said lines to displace that seam part formed by the moving line at an angle with respect to the axis of said rectangular sheet.

6 3. The method `of fabricating a blank as set forth in References Cited claim 2 in which the movement of one of said lines away UNITED STATES PATENTS from the `opposite line occurs during an interval starting 1,995,364 3/1935 Shatkn 113 120 when the leading edge of said sheet is approximately 3,051,214 8/1962 Rutten E 72 181 three-fourths of the Way through its passage between said 5 l lines and stops as the trailing edge of said sheet leaves CHARLES W LANHAM, Pflmy Examinerthe last of said rolling mills. RICHARD J. HERBST, Examiner. 

1. THE METHOD OF FABRICATING A TAPERED PIPE FROM A RECTANGULAR SHEET OF METAL USING A ROLL FORMING MACHINE HAVING TWO LINES OF DRIVEN ROLLING MILLS DISPOSED IN SPACED PARALLEL RELATION WITH RESPECT TO ONE ANOTHER EXTENDING LONGITUDINALLY OF SAID MACHINE, AND WITH SAID LINES ADAPTED TO PROGRESSIVELY AND SIMULTANEOUSLY FOLD AND CRIMP OPPOSITE SIDE EDGES OF SAID SHEET AS SAID PASSES LONGITUDINALLY OF SAID MACHINE BETWEEN SAID LINES TO FORM INTERCONNECTABLE PARTS OF A SEAM COMPRISING THE STEPS OF: PROVIDING A RECTANGULAR SHEET OF METAL OF A SIZE TO HAVE IT OPPOSITE SIDE EDGES ENGAGED BY SAID LINES, PSSING SAID SHEET BETWEEN SAID LINES LONGITUDINALLY OF SAID MACHINE, MOVING ONE OF SAID LINES AWAY FROM THE OPPOSITE LINE APPROXIMATELY ONE-EIGHT OF AN INCH DURING THE PASSAGE OF SAID SHEET BETWEEN SAID LINES SUCH THAT THE SEAM PART FORMED BY THE MOVING LINE IS DISPLACED AT AN ANGLE WITH RESPECT TO THE AXIS OF SAID RECTANGULAR SHEET, FORMING SAID SHEET INTO A TAPERED CYLINDER, INTERCONNECTING SAID INTERCONNECTABLE PARTS TO FORM A SEAM, AND CRIMPING THE SMALLER END OF THE TAPERED PIPE THUS FORMED. 